Energetics Flashcards
suggest one reason why extracting vanadium is expensive other than the costs of heating the reaction mixture?
Calcium is produced in the reaction. This is expensive to extract because it requires an immense amount of electricity. Electrolysis.
The equation for the reaction of Aluminium with iron 3 oxides.
2AL + Fe2O3 –> Al2O3 + 2Fe
Identify two hazards with the process of making vanadium using HCL other than temp
HCL is corrosive and hydrogen gas is flammable.
Deduce why this process produces pure vanadium other than the fact purified VCL2 is used.
The only other product produces is HCL which is a gas and it can therefore escape.
Why does Cl4 have a bond angle of 109.5
This is due to it having no lone pairs and 4 bonding pairs. Therefore they repel each other equally and spread as far as possible.
the reaction of iron with antimony sulfide to form antinomy and iron 3 sulfide
3Fe + Sb2S3 –> 2sb + 3Fes
One substance that is manufactured directly from sulfur dioxide is formed in this reaction.
Sulfur Trioxide
Why is the method of extraction from antinomy from a low-grade core ore is described as a low-cost process
Because it is a single-step process
suggest one other source of error in the student’s experiment
It was incomplete combustion
Suggest one reason why using a powdered catalyst increases the rate of reaction
It increases the collision frequency and the contact between the solids.
Suggest one major reason why this method of extracting strontium is expensive
Aluminum extract requires a large amount of energy due to it being extracted by electricity.
Why does calcium have a higher melting point than strontium
calcium has a stronger attraction between the cations and the delocalized electrons
Write the equation for magnesium and cold water
Mg + 2H2O –> 2Mg (OH)2 + H2
Give a medical use for the magnesium compound formed in the reaction of magnesium with cold water
Magnesium oxide is used to relieve indigestion and neutralize stomach acids
deduce the role of the bacteria in this reaction
A catalyst to speed up the reaction
Standard enthalpy of combustion
This is the enthalpy change when one mole a substance is burnt in excess oxygen with all the reactants and products under standard conditions
What are standard conditions?
298K
100kpa
Standard enthalpy of formation
This is the enthalpy change when one mole of a substance is produced from its constituent elements under standard conditions.
Suggest two reasons why the value obtained by the student is different from the value calculated
- Reactants not in standard condition
- incomplete combustion
- Energy has been lost to the surroundings due to heat loss
state a change in volume of water that would cause a reduction in heat loss
Increase in volume as there is increased contact between the colorimeter and the water.
A 50g sample of water was used. Explain how you could measure out this water without using a gas syringe
Water has a known density of 1gcm3 and therefore a volume of 50cm3 could be measured out
write an equation for the fermentation reaction?
C6H1206 —> 2CH3 CH2OH + 2CO2
give two essential conditions for the reaction to produce a good yield of ethanol.
Enzymes from yeast and conditions are aerobically
Name the process used to produce a much more concentrated solution of ethanol from a dilute aqueous solution.
Fractional distillation
What is carbon neutral
this is that there is no net overall carbon dioxide emission to the atmosphere
Mean bond enthalpy
the average energy change over a range of molecules needed in breaking covalent bonds
deduce the steps needed to determine an accurate minimum temperature that is not influenced by heat from the surroundings
- Star a clock watch when the substance is added to water
- Record the temperature every min for 5 min
- Plot a graph temperature vs time
- extrapolate back to the time of mixing and determine the temperature
Lattice enthalpy of disassociation
enthalpy of solution = lattice enthalpy + hydration enthalpy of both ions.
- Rearrange the equation
- make sure that you x2 if the question mentions chloride ions
why is your answer from lattice enthalpy off disassociation for magnesium chloride
Mag ion is smaller than calcium ions, therefore, this attracts chloride ions more strongly due to ionic bonding.
